1. Field of the Invention
The present invention relates to a light emitting diode and a method for producing the same, particularly, to a light emitting diode suitable for side luminescence.
2. Description of the Prior Art
Conventionally, a large number of light emitting diodes of surface or plane mounting type have been used for portable phones and the other small electrical instruments, one typical configuration thereof is known in general, as shown in FIG. 9, for example.
The light emitting diode 1 has a structure in which a pair of substrate electrodes 3 and 4 is patterned on an upper surface of a glass epoxy substrate 2, a light emitting diode element 5 is fixed on one electrode 3 by means of a conductive adhesive (not shown) and an upper electrode 5a of the light emitting diode element 5 and the other electrode 4 are connected by a bonding wire 6, and the light emitting diode element 5 is sealed by a sealing body 7 formed from a transparent epoxy resin.
The aforementioned light emitting diode 1 is generally mounted on a surface of a motherboard 8 (see FIG. 10) and is often formed to emit light upward.
In recent, the light emitting diode is often used as a light source of a backlight for illuminating a screen of a liquid crystal display of a portable phone, for example.
In this case, the light emitting diode 1 is inserted into a hole 9 provided in the motherboard 8, from a side of a back surface of the motherboard and then the substrate electrodes 3 and 4 of the light emitting diode 1 are fixed on a print wiring 10 provided on the back surface of the motherboard 8 by a solder 11 to reflect perpendicularly light emitted upwardly from the light emitting diode 1 on a inclined end surface 14 of an optical wave-guide 13 which is disposed above of the motherboard 8 and to guide the reflected light into the optical wave-guide 13.
However, in such a method as to use the reflected light, there is a possibility of generating a loss of light, and further it is necessary to carry out a micro-adjustment of an reflected angle of light illuminated from the light emitting diode element 5 and an angle of the inclined end surface 14, because the optical wave-guide 13 is thinned.
Under the circumstances, the Applicant in the present application has proposed a light emitting diode of a generally T-character shape as shown in FIG. 11, as a light emitting diode of a side luminescence type to coincide an illuminated direction of light from the light emitting diode with an entered direction of light into the optical wave-guide (see Japanese Patent Laid-Open No. 2002-164583).
The light emitting diode 15 includes a upright section 17, base sections 16a and 16b extending rightward and leftward from the upright section 17, and a protrusion 18 projecting from a front surface of the upright section 17. The protrusion 18 is formed with a concave portion in which a light emitting diode element 19 is disposed.
The light emitting diode element 19 is sealed by a sealing body 20 which is formed by a transparent resin filled into the concave portion.
The light emitting diode 15 structured as described above is mounted on the motherboard 8 in such a manner that the light emitting diode 15 is inserted into the hole 9 of the mother board 8 from the back surface of the motherboard 8 and then upper surfaces of the base sections 16a and 16b are disposed upon the motherboard at two positions on a peripheral edge of the hole 9 in order to fix substrate electrodes 21a and 21b of the base sections 16a and 16b to a print wiring of the motherboard 8 by soldering and to conduct electrically them.
The light emitting diode having the structure as described above has advantageous effects that it is possible to illuminate an incident surface or side surface of the optical wave-guide 13 on the side of the surface of the motherboard 8 and to enter directly the light emitted horizontally from the light emitting diode element 19 in the side of the optical wave-guide 13.
However, because the aforementioned T-shaped light emitting diode 15 has such a structure that the protrusion 18 is formed on the front surface of the upright section 17, there is a problem that a center of gravity of the light emitting diode offsets forwardly and therefore an unbalance for inclining the light emitting diode generates when the base sections 16a and 16b are mounted on the peripheral edge of the hole 9 provided in the motherboard 8.